Hi guys(adsbygoogle = window.adsbygoogle || []).push({});

I hope you have time to take a look at my calculation and tell me if this is possible to achieve.

I have to make a project, where I have to rotate an object which will resist more and more to the rotation. The protocol is:

Rotate the object with a torque of 5 Nm until the resistance becomes too large and the rotation will stop - now take a picture of the objects position.

Do the same thing with torques of 10, 15, 20, 25 Nm.

Since we have to do this approximately 1000 times, I would like it to be as automatized as possible.

I´m thinking it should not be a problem to program the motor through an Arduino Uno, but I'm not quite sure how I program the motor to stop at a specific torque.

I´m thinking to get 5 Nm of torque:

I found these two formulas:

1. Power (kw) = Torque (Nm) x Speed (RPM) / 9.5488

2. I (A) = Power(kw) x 1000 / (n x U) = , where n is the motors efficiency

I have not used motors before, but I believe you can adjust the speed (RPM) and the current applied to the motor through Arduino? Will the voltage be steady throughout the process, if I i.e. get at 12 V motor - or will it change? (Then my calculation won't work)

So if I want a torque of 5 Nm and I set the speed of 20 RPM can I then do this:

1. Power (kw) = 5 Nm x 20 RPM / 9.5488 = 0.01 kw.

2. I (A) = 0.01 kw x 1000 / (0.9 x 12 V) = 0.93 A

So, I´m thinking I can just program the motor to run at 20 RPM and gradually increase the current from 0 to 0.93 A, and when reaching 0.93 A the motor will stop for 5 seconds (to take the picture) and then rewind back to the starting position before starting over?

I guess there is a problem with the motors efficiency (n) and friction and perhaps other variables, but it is not the most important that the motor exactly performs 5 Nm or 4.8 Nm for that matter - the important thing is that is gives the same torque each time.

I hope you can clarify if I can do this, and your welcome to comment on obvious error or problems I can run into.

Kind regards

Kasper

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# Basic understanding of the motors torque and programming wit

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